全 文 ：·Short Communication·
Direct Regeneration of Inflorescence from Callus in
Dracaena fragrans cv.Massangeana Hort.
LU Wen_Liang
(Institute of Botany , The Chinese Academy of Sciences , Beijing 100093 , China)
Key words:　Dracaena fragrans;regeneration of inflorescence
　　 In the biological field studies of the in vitro direct
regeneration of organs possess important significance not
only on the in vitro micropropagation of each organ in the
living body (it is more important in the studies of medical
science but also on the understanding of the mechanism of
individual organ differentiation.The studies of in vitro di-
rect regeneration of organs in the botanical field is more in
the lead than that in zoological and medical fields.Up to
now , almost all organs of the flowering plants can be di-
rectly regenerated in vitro.The direct regeneration of the
vegetative organs such as vegetative bud , embryoid and
root had long time being successfully achieved.In the re-
sent 20s years direct regeneration of most of the reproduc-
tive organs such as spikelet
[ 1] , flower bud[ 2] , tepal[ 3-5] ,
stamen
[ 4] , pistil[ 1 ,6] , style_stigma_like structure[ 5 , 6] , ov-
ule
[ 4 , 7]
and fruit_like structure[ 8] was also induced respec-
tively.In 1992 inflorescence was directly differentiated
from the stem apex cultured in vitro
[ 9] , but regeneration
of inflorescence from callus cultured in vitro is still a very
difficult task because it has to go through the processes of
dedifferentiation and redifferentiation.The present paper
reports the induction of direct regeneration of the inflores-
cence from the callus of a ligneous plant Dracaena fra-
grans cv.Massangeana Hort.
1　Materials and Methods
1.1　The growth of experimental materials and the
induction of inflorescence differentiation of the plant
Plants of Dracaena fragrans cv.Massangeana Hort.
Which were individually grown in pots in the experimental
field of this institute.The plants with 30 or more leaves
were used for experiments.The plants were induced to go
into the reproductive growth for differentiation of inflores-
cence under lower temperature(at(15±1)℃)for 30 d
in a daily cycle of 8 h of light from cool_white fluorescent
lamps(5 W·m-2)and 16 h of darkness.
1.2　Tissue culture
1.2.1 　Sterilization and excision of explants　The
whole inflorescence (Fig.1A)was excised from plant
when the pollen grains in antherwere at the tetrad to ear-
ly_unicellular stages.It was sterilized in 0.1% aqueous
mercuric chloride for 10min , then rinsed three times with
sterile distilled water.After that , perianth tube (about 2
mm in thickness), the cut_segments of inflorescence
branch axis(about 3 mm in thickness)and rachis(about
5 mm in thickness)were respectively excised from the in-
florescence and used as explants.
1.2.2　Culture 　The basic medium used was that of
Murashige and Skoog
[ 10] , supplemented with various ex-
ogenous hormones in different concentrations as designed.
The cultures were grown at(25±1)℃ in daily cycle of
9 h of light from cool_white fluorescent lamps(5 W·m-2)
and 15 h of darkness.
2　Results
2.1　The morphological observation of the inflores-
cence of Dracaena fragrans in vivo
The inflorescence of Dracaena fragrans belongs to
panicle , consists of a rachis with some bracts and some
inflorescence branches come out from each bract axil(Fig.1A , 1B).The inflorescence branch is composed of
an axis where many flower buds grow from its the upper
half(Fig.1B).
2.2　Callus induction
In the previous studies
[ 1 , 7] , we reported that the
hormone combinations of 6_BA and 2 , 4_D is efficacious
for inducing the callus formation from explants and regen-
erating the reproductive organs from the callus.The hor-
mone combinations of 1.0mg L 6_BA and 0.5 or 0.8mg
L 2 ,4_D , therefore , was used for inducting the callus for-
mation in this experiment.Experiments showed(Table 1)
that when 1.0 mg L 6_BA and 0.5 or 0.8 mg L 2 ,4_D
most of the explants excised from the perianth tube , the
inflorescence branch axis and the rachis could form the
callus with different frequencies.Among them the fre-
quency of the perianth tube was the highest (about
89.4%-90.8%), next was the inflorescence branch
axis(about 83.7%-87.9%), and rachis was the low-
est(about 80.3%-89.5%).The change of 2 , 4_D
concentration from 0.5 mg L to 0.8 mg L had some , but
not marked influence on the induction frequency of the
callus.However , the calli formed on the medium with
higher concentration of 2 , 4_D such as 1.0 mg L 6_BA
and 0.8 mg L 2 ,4_D lost the ability of organ regeneration
easily (Table 3), especially when prolonging the culture
time over one month on this medium.Therefore , the cal-
lus formed on the medium contained 1.0 mg L 6_BA and
0.5 mg L 2 ,4_D was used for inducing the organ
Received:2001-11-12　Accepted:2001-12-04
植　物　学　报　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　
Acta Botanica Sinica　2002 , 44(1):113-116
114　 植物学报　Acta Botanica Sinica　Vol.44　No.1　2002
regeneration.The callus formations of the three kinds of
explants(perianth tube , inflorescence branch axis and ra-
chis)had similar morphological process.In the first 40 d
post_inoculation the explant gradually began to expand ,
then its epidermis cracked open due to the formation of a
mass of fiberiform structure(Fig.1C)from its cortical tis-
sue , finally the fiberiform structure transformed gradually
into callus(Fig.1D).
Table 1　The effect of exogenous hormones on callus formation from
the three kinds of explants
Exogenous hormones
(mg L) % of callus formation from explants1)
6_BA 2 , 4_D Perianth tube Inflorescence
branch axis
Rachis
1.0 0.8 90.8±2.2 87.9±1.8 80.3±2.3
1.0 0.5 89.4±2.7 83.7±2.5 80.5±2.6
1)The data were an average value repeated three times.
2.3 　Direct regeneration of inflorescence from the
callus
The three kinds of calli formed by the three respec-
tive kinds of explants on the two separate media containing
1.0 mg L 6_BA , 0.8 mg L 2 ,4_D and 1.0 mg L 6_BA ,
0.5 mg L 2 , 4_D respectively were transferred onto the
media with combinations of different hormone concentra-
tions as showed in Table 2 and 3 to induce the regenera-
tion of inflorescence.The results showed(Table 2)that
the three kinds of calli formed on the medium with 1.0
mg L 6_BA and 0.5mg L 2 ,4_D though all could directly
differentiate into inflorescence , yet the calli from different
origins regenerated inflorescence only in media with spe-
cific combination of the hormone concentrations.For ex-
ample , the rachis callus had(14.3±1.6)% of flores-
cence regeneration only in the medium of 0.5 mg L 6_BA
and 0.5 mg L 2 ,4_D.The calli of the perianth tube and
the inflorescence branch axis had regeneration frequency
of(7.4±1.9)% and(10.5±2.1)% respectively on a
medium with 0.5 mg L 6_BA+0.1 mg L 2 ,4_D.In con-
trast , the frequencies of inflorescence differentiation from
the three kinds of calli formed on the medium with 1.0
mg L 6_BA+0.8 mg L 2 , 4_D were not as good as those
of the former (Table 3).The frequencies of the inflores-
cence differentiation of the callus of perianth tube and the
inflorescence branch axis were greatly reduced , accounted(5.5±1.4)% and (4.1±1.7)% respectively .No in-
florescence differentiation was observed form the rachis
callus.The morphological process of the inflorescence dif-
ferentiation in the three kinds of the calli was similar.
Taking the rachis callus formed on the medium with 1.0
mg L 6_BA and 0.5 mg L 2 , 4_D as an example , one
month after the transferrance of the callus onto the medi-
um with 0.5 mg L 6_BA and 0.5 mg L 2 , 4_D , a thick
and sturdy main bud with some bracts was firstly differen-
tiated.With further growth of the main bud around which
some strong lateral buds were gradually differentiated ,
each arising from one bract axil(Fig.1E).Finally , with
the gradual development of all lateral buds into inflores-
cence branch , a young inflorescence was formed (Fig.
1F).
Table 2　The effect of exogenous hormones on the regeneration of
inflorescence from callus＊
Exogenous hormones
(mg L)
% of regenerating the inflorescence
from calli1)
6_BA 2 ,4_D PTC IBAC RC
0.5 0.5 0 0 14.3±1.6
0.5 0.1 7.6±1.9 10.5±2.1 0
0.5 0.005 0 0 0
＊, the calli are formed respectively f rom the explants of the perianth tube
(PTC), inflorescence branch axis(IBAC)and rachis(RC)on the medium
with 1.0 mg L 6_BA and 0.5 mg L 2 , 4_D;1)al l data are the average values
of three repetitions.
Table 3　The effect of exogenous hormones on the regeneration of
inflorescence from callus＊
Exogenous hormones
(mg L)
% of regenerating the inflorescence
from calli1)
6_BA 2 ,4_D PTC IBAC RC
0.5 0.5 0 0 0
0.5 0.1 0 4.1±1.7 0
0.5 0.005 5.5±1.4 0 0
＊, the calli are formed respectively f rom the explants of the perianth tube
(PTC), inflorescence branch axis(IBAC)and rachis(RC)on the medium
with 1.0 mg L 6_BA and 0.8 mg L 2 , 4_D;1)all data in this Table are the
average values of three repetitions.
3　Discussion
The direct regeneration of the inflorescence proclaims
that the main reproductive organs of the flowering plant all
can be directly regenerated in vitro.By comparing the
methods used in these experiments , it was found that they
have something in common.Firstly , the explants used in
these experiments are all excised from the reproductive or-
gans;secondly , the exogenous hormones used are all the
combination of auxin and cytokinin and the concentration
of the cytokinin is higher than those of the auxin in the
→
Fig.1.　A.A terminal inflorescence of Dracaena fragrans.It consists of a rachis(R)with some bracts(B)and some inflorescence branches
(IB)which come out from the bract axil.Bar=4.00 cm.B.An enlargement of the upper part of an inflorescence.The flower bud(F), the
bracts(B), the inflorescence branch(IB)and the rachis(R)can be clearly seen.Bar =0.66 cm.C.The fibriform structure , which was
formed by cortical tissue of the rachis explant of D.fragrans before the formation of callus.Bar =0.28 cm.D.The callus.It is formed by
further development of the fibriform structure derived from the perianth tube explant of D.fragrans.Bar =0.10 cm.E.The regenerated in-
florescence at its early stage.It is directly differentiated from the rachis callus of D.fragrans.The bracts(B)and the inflorescence branch
(IB)can be clearly seen.Bar = 0.10 cm.F.The young inflorescence formed by further development of the inflorescence at the early stage
in D.fragrans , consisted of a rachis(R)and some inflorescence branches(IB)arising from the bract(B)axil.Bar=0.28 cm.
LU Wen_Liang:Direct regeneration of inflorescence from callus in Dracaena fragrans cv.Massangeana Hort. 115　
combinents.It shows to exist some regularities among
them.Unfortuntely it is still not clear in their connotation
as well as the mechanism.Wish our present knowledge ,
to induce the regeneration of specific_given organs is still
very difficult.It requires to propose a new idea and ap-
proaches to attach this problem.Perhaps , this is the most
pressing matter of the moment.
Acknowledgements:The author thanks Professor BAI
Shu_Nong for technical assistance in preparing the fig-
ures.
References:
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花叶千年木愈伤组织直接再生花序
陆文木梁
(中国科学院植物研究所 , 北京 100093)
摘要:　以花叶千年木(Dracaena fragrans cv.Massangeana Hort.)的花被筒 、花序分枝轴和花序轴为外植体成功地诱
导了花序的直接再生。3种外植体首先在MS 附加 1.0 mg L 6_BA 和 0.5_0.8 mg L 2 , 4_D 的培养基上诱导形成愈伤
组织 ,然后转移到 MS 附加 0.5 mg L 6_BA 和 0.005 ～ 0.5 mg L 2 , 4_D的培养基上分别诱导了花序的直接再生。观察
了愈伤组织形成和花序分化的形态学过程。
关键词:　花叶千年木;花序直接再生
中图分类号:Q943.1　　　文献标识码:A　　　文章编号:0577-7496(2002)01-0113-04
收稿日期:2001-11-12　接收日期:2001-12-04
(责任编辑:李长复)
116　 植物学报　Acta Botanica Sinica　Vol.44　No.1　2002